1. Field of the Invention
This invention relates to electrical cable constructions and, more particularly, this invention relates to improved communication cable constructions.
2. Description of the Prior Art
In the art of designing electrical cables, especially communication cables, conductors are generally assembled in a core which is surrounded by an outer shield (such as a sheath) and a jacket.
The shield is generally metallic, and the protective jacket is typically a polyolefin, such as polyethylene. In some cables, especially where the number of conductors in the core is very large or the cable very long, a screen, usually comprising a ribbon of metal such as aluminum, for example, extends through the multiconductor core. The screen is intended to prevent cross talk between cable pairs of the core, and can be in the shape of an S, Z, D, or T, or any other appropriate configuration.
Heretofore, the screen extended through the core has typically been prepared with a film of polypropylene or an oriented polyester resin laminated thereto. These constructions are stiff, resulting in buckling during the cable making operation, leading to an unusable cable.
In some cables, the cable core is filled with a cable filler material designed to prevent moisture from entering the cable. During the manufacture of the cable, the filler is heated to make it flowable. Such heating is accomplished by induction heating. If the screen becomes buckled or folded, the induction heating causes localized overheating in the screen, resulting in a temperature high enough to melt the polymeric coating of the screen, thus rendering the cable inoperative.